The war in the Pacific would have likely ended only after a brutal and spectacularly bloody invasion of Japan by US ground troops (which was in the advanced planning stages in 1945). Millions of people would have died, including hundreds of thousands of American soldiers; and the losses in Japan would have been catastrophic. It would have been one of the most horrific chapters of the war. I also think that had this scenario played out, postwar Japan would likely not have been anything like the Japan that actually was rebuilt after 1945.

I should think that the US would've compromised over the issue of the Emperor and the Japanese would've surrendered 'unconditionally'. If not before the Soviet declaration of war, then certainly pretty soon afterwards!!

I doubt it. We weren't willing to accept Japan's conditional surrender even before we could reasonably assume that our atomic weapons would actually work in combat. Even with our plans to drop the bombs, we were still planning to invade. The intransigence of the Japanese military rulership had left us with few legitimate options.

It's the choice of a conditional surrender with only one condition, the Emperor or 100,000 dead soldiers and the possbility of Russia grabbing part of Japan. The US army were crazy enough to want to invade but Truman was a pragmatist.

I should think that the US would've compromised over the issue of the Emperor and the Japanese would've surrendered 'unconditionally'. If not before the Soviet declaration of war, then certainly pretty soon afterwards!!

I agree that the Soviet declaration of war should have made some of the Japanese generals seriously consider the inevitable, but rationality wasn't the issue. By August of 1945, Japan had already lost the war (whether the Soviets jumped against them in or not). All that remained was the defense of the Japanese homeland against a final invasion. The Japanese leadership seemed determined to defend every inch of Japanese soil, even if it meant turning the entire country and all of its citizens into ash. I still doubt that they would have easily capitulated.

Japanese offered surrender twice before the first nuke went off conditional on the emperor is left alone. US turned both offers down. So the Japanese were willing to surrender, they had made their choice. It's also the US not the Japs who have to worry about the Russians.

For the US its the choice of a conditional surrender with only one condition, the Emperor or 100,000 dead soldiers and the possbility of Russia grabbing part of Japan. The US army were crazy enough to want to invade but Truman was a pragmatist.

Trinity was on 16 July. Even before the successful test, a second bomb had already been shipped out the Pacific. If you have a bomb, you're probably going ot use it. At Potsdam, on 26 July, the 'Allies' announce that 'We will not deviate from them. There are no alternatives. We shall brook no delay.' If you've got a weapon such as the atomic bomb, you can afford to make pretty stringent demands.

I reckon that without the bomb, the US would've been more discrete and would've gladly have accepted a surrender that allowed the Emperor to remain. Not only were the official estimates for an invasion (and we've already had a similar discussion) 50,000 (-100,000) casualties, but the US were under increasing domestic pressure to start bringing the troops home. The US public had no appetite for more dead troops. All the arguments against invasion were compelling and on the table. The bomb was a way out.